Necrotizing enterocolitis (NEC) is a life-threatening inflammatory bowel disorder that affects approximately 10% of premature infants with a birth weight lower than 1500 grams. The pathophysiology of NEC is not completely understood and therapy is currently only supportive. Means of preventing this disease or treating it in its early stages may provide clinical benefit. Human milk has been shown to be protective against NEC in clinical studies. The objective of this study is to investigate whether the human milk factors erythropoietin (Epo) and transforming growth factor-beta (TGF-b) have protective effects against NEC and to study the underlying mechanisms of this protection using cell and animal models. The intestinal epithelium forms a relatively impermeable barrier that can be maintained by proper tight junction (TJ) structure and protein expression. Disruption of the TJ can lead to hyper-permeability of the gut, predisposing the host to bacterial translocation and immune system activation in the pathogenesis of NEC. Besides barrier function, the pathogenesis of NEC is associated with exaggerated cytokine responses and extensive inflammation that can be governed by the pro-inflammatory factor NF-kB. Previous studies have shown a role for Epo in protection of cell-cell barrier in endothelial cells and the blood-brain barrier in animals. My preliminary data show that the human milk factor Epo positively regulates enterocyte barrier function by regulating tight junction (TJ) protein expression. Another human milk factor TGF-b has been shown to negatively regulate NF-kB in rheumatoid synovial fibroblasts. My preliminary data demonstrate TGF-b suppression of NF-kB in human fetal immature intestinal epithelial cells. Thus, previous observations and my preliminary data strongly support the hypothesis that the human milk factors Epo and TGF-b may lower the incidence of NEC by protecting intestinal barrier function and inhibiting exaggerated inflammatory responses and apoptosis. Improved understanding of the pathogenesis in this disease may allow the development of therapeutic agents that can prevent or ameliorate NEC in immature infants. PUBLIC HEALTH RELEVANCE: Necrotizing enterocolitis is a poorly understood, life threatening inflammatory bowel disease of premature infants with 20-30% mortality rate. Two factors found in human breast milk, Erythropoietin (Epo) and Transforming growth factor-beta (TGF-b) are believed to have protective effects against this disease. This proposal will investigate how Epo and TGF-b protect immature intestine, in order to develop a treatment to prevent or ameliorate NEC in vulnerable infants.